Index: .github/workflows/ci-sage.yml
===================================================================
--- .github/workflows/ci-sage.yml	(revision 5598f5b3a59a00339cefa7a50bd9d845ae30f8e9)
+++ .github/workflows/ci-sage.yml	(revision 0c72bd59e147029295d142d75f97ec41ea04f6ae)
@@ -89,4 +89,88 @@
           name: upstream
 
+  kanarienvogel:
+    # Quick run for 1 platform first; do not run the other platforms when this already fails
+    runs-on: ubuntu-latest
+    needs: [dist]
+    strategy:
+      fail-fast: true
+      max-parallel: 4
+      matrix:
+        tox_system_factor: [ubuntu-focal]
+        tox_packages_factor: [standard]
+    env:
+      # Override so that this runs faster
+      TARGETS: SAGE_CHECK=no singular
+      TARGETS_OPTIONAL: build/make/Makefile
+    # The rest of this is identical to job "docker":
+      TOX_ENV: docker-${{ matrix.tox_system_factor }}-${{ matrix.tox_packages_factor }}
+      LOGS_ARTIFACT_NAME: logs-commit-${{ github.sha }}-tox-docker-${{ matrix.tox_system_factor }}-${{ matrix.tox_packages_factor }}
+      DOCKER_TARGETS: configured with-targets with-targets-optional
+    steps:
+      - name: Check out SageMath
+        uses: actions/checkout@v2
+        with:
+          repository: ${{ env.SAGE_REPO }}
+          ref: ${{ env.SAGE_REF }}
+        if: env.SAGE_REPO != ''
+      - name: Check out git-trac-command
+        uses: actions/checkout@v2
+        with:
+          repository: sagemath/git-trac-command
+          path: git-trac-command
+        if: env.SAGE_TRAC_GIT != ''
+      - name: Check out SageMath from trac.sagemath.org
+        shell: bash {0}
+        run: |
+          if [ ! -d .git ]; then git init; fi; git remote add trac ${{ env.SAGE_TRAC_GIT }} && x=1 && while [ $x -le 5 ]; do x=$(( $x + 1 )); sleep $(( $RANDOM % 60 + 1 )); if git-trac-command/git-trac ${{ env.SAGE_TRAC_COMMAND }} $SAGE_TICKET; then exit 0; fi; sleep 40; done; exit 1
+        if: env.SAGE_TRAC_GIT != ''
+      - uses: actions/download-artifact@v2
+        with:
+          path: upstream
+          name: upstream
+      - name: Install test prerequisites
+        run: |
+          sudo DEBIAN_FRONTEND=noninteractive apt-get update
+          sudo DEBIAN_FRONTEND=noninteractive apt-get install tox python3-setuptools
+      - name: Update Sage packages from upstream artifact
+        run: |
+          (export PATH=$(pwd)/build/bin:$PATH; (cd upstream && bash -x update-pkgs.sh) && sed -i.bak '/upstream/d' .dockerignore && echo "/:toolchain:/i ADD upstream upstream" | sed -i.bak -f - build/bin/write-dockerfile.sh && git diff)
+      - name: Configure and build Sage distribution within a Docker container
+        run: |
+          set -o pipefail; EXTRA_DOCKER_BUILD_ARGS="--build-arg USE_MAKEFLAGS=\"-k V=0 SAGE_NUM_THREADS=3\"" tox -e $TOX_ENV -- $TARGETS 2>&1 | sed "/^configure: notice:/s|^|::warning file=artifacts/$LOGS_ARTIFACT_NAME/config.log::|;/^configure: warning:/s|^|::warning file=artifacts/$LOGS_ARTIFACT_NAME/config.log::|;/^configure: error:/s|^|::error file=artifacts/$LOGS_ARTIFACT_NAME/config.log::|;"
+      - name: Copy logs from the Docker image or build container
+        run: |
+          mkdir -p "artifacts/$LOGS_ARTIFACT_NAME"
+          cp -r .tox/$TOX_ENV/Dockerfile .tox/$TOX_ENV/log "artifacts/$LOGS_ARTIFACT_NAME"
+          if [ -f .tox/$TOX_ENV/Dockertags ]; then CONTAINERS=$(docker create $(tail -1 .tox/$TOX_ENV/Dockertags) /bin/bash || true); fi
+          if [ -n "$CONTAINERS" ]; then for CONTAINER in $CONTAINERS; do for ARTIFACT in /sage/logs; do docker cp $CONTAINER:$ARTIFACT artifacts/$LOGS_ARTIFACT_NAME && HAVE_LOG=1; done; if [ -n "$HAVE_LOG" ]; then break; fi; done; fi
+        if: always()
+      - uses: actions/upload-artifact@v2
+        with:
+          path: artifacts
+          name: ${{ env.LOGS_ARTIFACT_NAME }}
+        if: always()
+      - name: Print out logs for immediate inspection
+        # and markup the output with GitHub Actions logging commands
+        run: |
+          .github/workflows/scan-logs.sh "artifacts/$LOGS_ARTIFACT_NAME"
+        if: always()
+      - name: Push Docker images
+        run: |
+          if [ -f .tox/$TOX_ENV/Dockertags ]; then
+            TOKEN="${{ secrets.DOCKER_PKG_GITHUB_TOKEN }}"
+            if [ -z "$TOKEN" ]; then
+              TOKEN="${{ secrets.GITHUB_TOKEN }}"
+            fi
+            echo "$TOKEN" | docker login docker.pkg.github.com -u ${{ github.actor }} --password-stdin
+            for a in $(cat .tox/$TOX_ENV/Dockertags); do
+              FULL_TAG=docker.pkg.github.com/$(echo ${{ github.repository }}|tr 'A-Z' 'a-z')/$a
+              docker tag $a $FULL_TAG
+              echo Pushing $FULL_TAG
+              docker push $FULL_TAG
+            done || echo "(Ignoring errors)"
+          fi
+        if: always()
+
   cygwin:
     env:
@@ -105,5 +189,5 @@
     runs-on: windows-latest
 
-    needs: [dist]
+    needs: [dist, kanarienvogel]
 
     strategy:
@@ -188,5 +272,5 @@
   docker:
     runs-on: ubuntu-latest
-    needs: [dist]
+    needs: [dist, kanarienvogel]
     strategy:
       fail-fast: false
@@ -277,5 +361,5 @@
         xcode_version_factor: [11.7, default, 12.3]
 
-    needs: [dist]
+    needs: [dist, kanarienvogel]
 
     env:
